1. Field of the Invention
The present invention pertains to fiber optic communications systems and, more particularly, to optical crossconnect configurations utilizing micro electromechanical systems (MEMS) tilting mirror arrays.
2. Description of the Related Art
In fiber optic communication systems, signal routing is essential for directing an optical signal carrying data to an intended location. Existing routing techniques typically experience optical power loss due to inefficient coupling of optic signals between input and output fibers. This increases the dependence on optical power sources (e.g., pump lasers) which are used to compensate for power losses by injecting optical power back into the optical system. The need for optical power sources increases the overall cost of the optical system.
Another criteria for signal routing is the ability to direct a signal received from one of a plurality of input fibers or ports to any of a plurality of output fibers or ports without regard to the frequency of the optical signal. Known optical signal routers are frequency dependent so that frequency dictates the routing of multiple signals, each signal having a discrete wavelength, to output ports based on the signal frequency. For example, and as disclosed in commonly-owned U.S. patent application Ser. No. 09/414,622, filed Oct. 8, 1999, multiple adjacent-in-frequency wavelengths will be routed to adjacent-in-space output fibers, as opposed to randomly selected output fibers. Accordingly, an optical crossconnect system is desired having flexible frequency routing capability with reduced power loss.
Improvements over known optical crossconnects are realized by providing an optical crosssconnect utilizing an array of tilting micro-electromechanical systems (MEMS) mirrors for directing optical signals from input optic fibers to output optic fibers. The optical crossconnect includes a lens array for receiving optical signals from a plurality of input fibers. The lens array is made of up a plurality of lens elements, with each lens element directing or focussing an optical signal to a MEMS mirror array. The MEMS mirror array includes a plurality of mirror elements, each being tiltable about one or more rotational axes upon the application of control signals to the desired mirror elements. In this manner, optical signals can be directed along various paths and to various output fibers.
In a preferred embodiment, input and output lens arrays are used in conjunction with input and output MEMS mirror arrays. The input lenses direct input optical signals to the input MEMS array which, in turn, reflects each signal in a direction relative to each mirror""s tilt orientation. The reflected signals are received and further reflected by the output MEMS mirror array to the output lens array for coupling to output fibers.
In another preferred embodiment, input and output lens arrays are formed on a common substrate, with a reflective surface disposed therebetween, and input and output MEMS mirror arrays are formed on a second common substrate disposed in opposing relation to the first substrate. The reflective surface receives reflected optical signals from the input MEMS array and directs them to the output MEMS array.
In yet another embodiment, an optical element having transmissive properties is disposed in optical communication with a first MEMS mirror array and a second MEMS mirror array. The optical element directs optical signals, either by transmission or reflection, between the first and second mirror arrays to selectively forward optical signals between a first fiber array and a second fiber array.